Acquisitions - Washington Acquisition (Details) mbpd in Thousands, barrel / d in Thousands, shares in Millions, bbl in Millions		1 Months Ended	3 Months Ended			9 Months Ended
	Jan. 11, 2019 USD ($) mbpd shares bbl	Jan. 31, 2019 USD ($)	Sep. 30, 2019 USD ($) barrel / d	Mar. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) barrel / d	Sep. 30, 2018 USD ($)	Jan. 09, 2019 USD ($)
Business Acquisition [Line Items]
Oil and gas refinery capacity | barrel / d			200			200
Issuance of common stock for business combination	$ 37,000,000.0			$ 36,980,000
Acquisition and integration costs			$ 623,000		$ 2,134,000	$ 4,325,000	$ 3,515,000
Income tax expense (benefit)			(2,428,000)		$ 359,000	(69,002,000)	$ 885,000
Term Loan | Term Loan B Facility
Business Acquisition [Line Items]
Debt instrument, face amount	250,000,000.0
Term Loan | Par Pacific Term Loan
Business Acquisition [Line Items]
Debt instrument, face amount								$ 45,000,000.0
Washington Acquisition
Business Acquisition [Line Items]
Consideration transferred, gross	$ 358,000,000
Oil and gas refinery capacity | mbpd	42
Oil and gas storage capacity | bbl	2.9
Consideration transferred	$ 326,500,000
Cash consideration transferred	$ 289,500,000
Common stock offering, net of issuance costs (in shares) | shares	2.4
Acquisition and integration costs		$ 5,400,000				2,200,000
Adjustment, property, plant, and equipment			2,100,000
Adjustment, deferred tax liability			5,900,000
Adjustment, working capital adjustment			(1,900,000)
Goodwill, purchase accounting adjustments			(6,100,000)
Revenue			300,000,000.0			855,600,000
Earnings (loss) of acquiree since acquisition date, actual			$ 29,400,000			49,500,000
Income tax expense (benefit)						$ (67,000,000.0)